The logo of Dow Jones Industrial Average stock market index listed company United Technologies and their subsidiary Pratt & Whitney is pictured in San Diego, California April 21, 2016. REUTERS/Mike Blake

Eleven aircraft operated by Indian carriers IndiGo and GoAir are affected by the directive from India’s Directorate General of Civil Aviation (DGCA), it said.

DGCA said it had also asked the airlines not to replace the engines.

On Monday a flight operated by IndiGo, India’s biggest low-cost carrier, experienced a technical glitch with one of its engines.

It was forced to return to Ahmedabad airport, in western India, the airline, which is owned by InterGlobe Aviation (INGL.NS), said in a separate statement.

DGCA said there had been three such incidents in 2018 - two involving IndiGo and one with an GoAir aircraft.

In February, the U.S. aviation regulator said the Pratt & Whitney engines pose a shutdown risk, following similar action by European regulators that month.

Indian airlines have hundreds of A320neo planes on order but they, among other carriers, are facing delivery delays due to problems with the engines.

“We are working closely with our customers to minimize disruption. The corrective action has been approved and we have already begun to deliver production engines with the upgraded configuration. We are working to mitigate the ...situation by the end of the second quarter,” said a statement from Pratt, a unit of United Technologies Corp (UTX.N).

DGCA said it would remain in touch with the stakeholders including the European Aviation Safety Agency.

Eight aircraft operated by IndiGo and three by GoAir will need to be grounded, it said.